1.5 Theory of Plate Tectonics


Vocabulary


Plates: the lithosphere is broken into seperate sections
Scientific Theory: a well tested concept that explains a wide range of observations
Plate Tectonics: geological theory that states the pieces of earth's lithosphere are in constant, slow motion, driven by convection currents in the mantle
Faults: breaks in earth's crust where rocks have slipped past each other
Transform Boundary: place where two plates slip past each other, moving in opposite directions
Divergent Boundary: place where two plates move apart
Convergent Boundary: place where two plates come together
Rift Valley: deep valley that forms along the divergent boundary

Outline


Theory of Plate Motion


  • Wilson combined what the geologists knew about sea floor spreading, and all the other lessons about the earth into a single theory which is the theory of plate tectonics
    • explains the subduction, formation, and movement of Earth's plates
  • convection currents rise in the asthenosphere and spreads out beneath the lithosphere
  • change produces in earth's surface
    • volcanoes
    • mountain ranges
    • deep sea trenches
Plate Boundaries


    • 3 types of plate boundaries are: transform, divergent, and convergent boundaries
      • Transform boundary is a place where two plates slip past each other, moving in opposite directions
      • Divergent boundary is where two plates move apart
      • Convergent boundary is where two plate come together
  • The Continent's Slow Dance
    • the plates move at a really slow rate, about 1-10 centimeters per year
    • long ago continents were joined together, forming a supercontinent Wegener called Pangaea
      • Later, Pangaea broke apart